A device known as a mouse is used for transforming movements into controls required by a user. The mouse is formed by a box equipped with electronic means connected to the computer for transforming the movements of the box on the working surface into a movement of the cursor or pointer on the computer screen.
Thus, a mouse more generally includes a ball for rolling over the working surface, sensors to detect the movements of the ball and means for processing the electric signals of the sensors. The processing means are connected to the computer by an electric cable or a Hertzien or infrared link. The processing means have been designed to deliver signals recognised by the protocol of the port to which the mouse is connected, usually corresponding to the standard RS 232. However, the mouse can also be connected to the computer via a dedicated interface card or to a specific bus in which case the processing means shall deliver one or several signals recognised by the protocol associated with this interface card or bus.
The mouse may in addition include a certain number of push or scrolling buttons which are also connected to the processing means and which correspond to validation or data entry function according to the operating mode of the computer.
The means for processing the signals derived from the movement sensors and the position sensors of the scrolling or input buttons then provide several principal functions, namely:
detection of the movement of the mouse,
detection of the position of the push-buttons,
and communication with the computer as per the retained standard.
Communication with the microcomputer is more usually managed by a microprocessor ensuring the two parts of the processing of the signals derived from the movement and position detectors of the push-buttons. The mouse also contains means to control the electric feeding of the means for processing the signals and possibly that of the movement detection and position sensors.
Finally, the mouse is associated with a control software loaded into the computer which decodes the signal transmitted by the mouse. The driver provides the application software requesting it information concerning the state and status of the mouse: firstly the movement and secondly the position of the push-buttons so as to enable them to carry out the resultant actions.
In its most frequently used operating mode, the driver communicates with the sub-programme or movement routine of the cursor or pointer when the mouse is moved and sends messages to the programme when the push-buttons of the mouse are pressed.
It ought to be said that for most of the drivers used, the movement of the pointer on the screen does not correspond directly to that of the mouse. In fact, it has been observed that the movement of the mouse can be broken down into two main movements, namely movement of the mouse until the pointer is brought into the desired zone and then its precise positioning on the targeted point or object. Thus, when the mouse is moved slowly, the driver generates a movement of the pointer on the screen of about 100 CPI (Counts Per Inch) or DPI (Dots Per Inch), and when the mouse is moved quickly, the driver generates a movement of the pointer of about 400 CPI, indeed 1000 CPI.
According to the prior art, the mouse gives full satisfaction as a control peripheral of a computer when using the hand.
However, it may appear necessary to be able to control a computer or electronic system without resorting to using the hands, especially when the user is unable to do so.